1. Field of the Invention The present invention relates to a process for purifying at least 90% pure n-butyl chloride which is present in mixtures with other C.sub.1 to C.sub.4 alkyl chlorides, C.sub.1 to C.sub.4 alcohols, esters, ketones, nitrites, and organic sulfur compounds, via distillation and washing of the distillate.
2. Description of the Background
Alkyl chlorides are valuable solvents. Furthermore, n-butyl chloride is an important intermediate for preparing a variety of organometallic compounds and crop protection agents and pharmaceutical products.
The preparation of n-butyl chloride generally starts from n-butanol and hydrogen chloride. Minor components which occur in the preparation are butanes, isomeric chlorobutanes, n-butanol and di-n-butyl ether. Therefore, purification processes generally only concern removing these byproducts.
Thus, in EP-B-0,392,270, all of the reaction product of the continuous reaction of C.sub.3 to C.sub.4 monoalkanols with hydrogen chloride is initially taken off in the vapor state for work-up. The mixture is then cooled, phase separation is induced and the phases are then further worked up separately. The alkyl chloride phase is washed with water, dried and, if appropriate, purified by a two-stage continuous distillation.
In German Patent 462,993, n-butanol is reacted with hydrochloric acid under pressure. The reaction product is washed with soda solution (sodium carbonate solution).
According to DD 138 470, the reaction of n-butanol with hydrochloric acid in a reactor having an attached column is carried out in such a manner that the di-n-butyl ether produced in small amounts as byproduct predominantly remains in the reactor. At the top of the column, a mixture is taken off which predominantly comprises water and n-butyl chloride. After the phase separation, the n-butyl chloride phase is washed in counter-current with weakly alkaline water.
Accordingly, the purification processes described above are essentially restricted to separating off n-butanol, isomeric chlorobutanes and d-in-butyl ether from the desired n-butyl chloride.